JPH10303928A - Exchange device for atm network, traffic management device and exchange method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an interface for a segmentation and reassembly(SAR) device in an ATM(asynchronous transfer mode) exchanging device. SOLUTION: A switch body 8 to exchange an ATM cell, the segmentation and reassembly(SAR) device 12 to reassemble a packet from the ATM cell and plural traffic management(TM) devices 241 to 24N are included in the exchanging device to be used in the ATM network. Each TM device 24 is connected with the switch body by a first data transmission route 10 and directly connected with the SAR device 12 by a second data transmission route 26 so as to receive the ATM cell transmitted to a port attached to the exchanging device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to segmentation-and-reassembly (SAR) in asynchronous transfer mode (ATM) switching equipment.
easemly) for interfacing to devices.

[0002]

2. Description of the Related Art FIG. 1 of the accompanying drawings shows an ATM communication network.
Parts of conventional switching equipment for use in
You. 1 includes a plurality of N-1 physical layer devices 2
₁, 2_Two… 2_N-1And corresponding N-1 traffic
Lock management device 4₁, 4_Two… 4 _N-1Comprising. each
Various traffic management devices 4_iIs a two-way data transmission
Route 6_iThe corresponding physical layer device 2
_iIt is connected to the.

The device of FIG. 1 also includes a switch body 8 which is, for example, an N × N cross-connect switching unit. Actually, the switch body 8 has N input ports and N output ports. Each traffic management device 4 _i is connected by a bidirectional data delivery path 10 _i to one port pair consisting of one input port and one output port. Thus, for simplicity, only port pairs are shown in FIG.

The apparatus of FIG. 1 also includes a segmentation-and-reassembly (SAR) device 12 connected to a port pair N of switch body 8 by a bidirectional data delivery path 10 _N. This SAR device 12 is connected to an associated memory 14. Finally, device 1 includes a host processor (or switch control unit) 16, each memory traffic management device 4 ₁ to 4 _N-1 is connected to the 14.

[0005] In use of the apparatus of FIG. 1, the physical layer devices 2 ₁ to 2 _N-1, compared apparatus 1, a plurality of bidirectional ports connected to the physical layer transmission line (user network interface or UNI port) I will provide a. These physical layer transmission lines are, for example, synchronous digital hierarchy (SDH) or synchronous optical communication network (SONET) transmission lines (ITU-T standard G.70).
9), Plesiochronous Digital Hierarchy (PD
H) Transmission line (ITU-T G.703 standard) or Fiber Distribution Data Interface (FDDI) transmission line (4b / 5b specified by ATM Forum)
Standard). Within an ATM network, these transmission lines carry ATM cells in a bitstream format having a format that depends on the particular physical medium used to provide the relevant transmission line. In the data reception direction (cell is received within the switching equipment), physical layer devices 2 ₁ ~2 _N-1 is, UN equipment
The bit stream received by the I port, via the respective data delivery route 6 ₁ ~6 _N-1 is converted into a stream of ATM cells to be delivered to the traffic management device 4 ₁ ~4 _N-1.

The traffic management devices 4 ₁ to 4
_N-1 controls the transmission of ATM cells to the switch body 8. The switch body 8 provides up to N simultaneous data transfer paths each serving to enable data transport from a selected one of its input ports to a selected one of its output ports. be able to. Traffic management devices use these data transfer paths to synchronously exchange ATM cells. The overall control of the exchange process is usually
It is performed by the host processor 16 to monitor traffic flow conditions and select data transfer paths in consecutive time slots to provide a fair allocation of switching resources between different cell flows through the device.

[0007] The traffic management device 4 sends the AT through one of the data transfer paths provided by the switch body.
After receiving the M cell, it forwards the cell via the data delivery path 6 to its corresponding physical layer device. Each physical layer device 2 converts the received ATM cell stream into a bit stream suitable for transmission on an ATM transmission line connected to the UNI port of the physical layer device.

In an ATM network in which the apparatus shown in FIG. 1 is used, most, if not all, of the ATM cell traffic transmitted is composed of user data, regardless of whether they represent voice signals, video signals, files, or the like. It is. However, some traffic transmitted by the network inevitably includes control information such as signaling messages. Such signaling messages are needed, for example, to set up a call. Furthermore, it may be necessary for host processors to interact with each other at different nodes of the ATM network (including host processor 16 shown in FIG. 1) using so-called "host-to-host communication messages".

[0009] Signaling messages and host-to-host communication messages are transferred within the ATM network in the form of ATM cells, just like normal data traffic. However, cells constituting such a message are distinguished in some sense from cells representing data by virtual path identifier (VPI) and virtual channel identifier (VCI) information included in the header of each cell. Is done. Signaling messages and inter-host communication messages are generally too long to fit within the payload of a single ATM cell. Thus, at the source of each such message, the message is converted into a plurality of ATM cells, which are then continuously fed into the network. This process is called segmentation. AT at which it is desired to access the message, and possibly to the message
At any intermediate node of the M-network, the ATM cells that make up the message regenerate the original message when combined in a process called reassembly. In the switching device shown in FIG. 1, these segmentation and reassembly processes are conventionally performed with the segmentation and reassembly (SAR: SAR) of the switch body 8 having its own dedicated port pair (port N in FIG. 1). segmentat
ion-and-reasembly) device 12
Will be implemented. Therefore, the AT indicating in its VPI / VCI field that it belongs to a signaling message or a host-to-host communication message
When the host computer 16 receives information that an M cell has been received by one of the traffic management devices 4 (the "source" traffic management device), the host processor 16 determines which switch the source traffic management device is connected to. A data transfer path is formed from the input port of the switch 8 (for example, the input port _{1 in} the case of the traffic management device 41) to the output port N of the switch 8 so that the cell is connected from the source traffic management device to the SAR device 12. Can be sent. The SAR device 12 can then use the memory 14 to combine this cell with other cells belonging to the same message and read the message by the host processor 16 once the reassembly process for that message has been completed. Becomes

If the host processor 16 is the source of the signaling or inter-host communication message, it sends the message to the memory 14 and the SA
The R device 12 then segments the message,
Generate a plurality of ATM cells. These cells are then traffic traffic, such as a traffic management device, whose corresponding physical layer device is connected to the transmission line through which the cell must be routed to reach the message destination. It is continuously transferred to one of the management devices (the "destination" traffic management device). Under the control of the host processor 16, one data transfer is performed for each successive cell of a message from the input port N of the switch body 8 to the output port of the switch body to which the destination (destination) traffic management device is connected. A route is provided. After arriving at this destination traffic management device 4, the cell is then passed over the data delivery path 6 to the corresponding physical layer device 2,
It is output to the requested transmission line through one of the UNI ports for further transmission to the destination of the message.

[0011]

SUMMARY OF THE INVENTION In the apparatus shown in FIG.
The SAR device 12 has its own dedicated port pair (port N) on the switch body, so that all signaling messages and inter-host communication messages pass through the switch body 8. Although the number of ATM cells involved in such a message is relatively small compared to the total number of ATM cells passing through the switch body, there is a need to pass the ATM cells constituting the signaling and inter-host communication messages through the switch body. This inevitably causes congestion in the switch body and reduces the number of opportunities to exchange ATM cells representing user data. In addition, the number of port pairs available for connection with the traffic management device is reduced by one, since one of the switch body port pairs must be dedicated to the SAR device 12. This is ultimately
Overall, the number of UNI ports of the switching device is limited.

Accordingly, an object of the present invention is to provide a switching device, a traffic management device, and a switching method in an ATM network that can solve the above-mentioned problem.

[0013]

According to a first aspect of the present invention, a switching device for exchanging ATM cells in an exchange device for use in an ATM network;
Reassembly means for reassembly of packets from TM cells, and connected to receive ATM cells transmitted to the switching device, and to the switch body by first data delivery path means and to the first switch body; A second data delivery path means separate from the data delivery path means is connected to the reassembly means and further comprises one or more predetermined packet types requiring reassembly by the reassembly means. Operable to identify a received ATM cell to which it belongs as a respective reassembly cell, and to receive cells other than such identified reassembly cells, and also to the first data delivery for exchange by the switch body. Operable to transmit to the switch body via the routing means, and reassembling the reassembled cell by the reassembly means. The order reassembled packet second
A traffic management means operable to transmit to said reassembly means via said data delivery path means.

According to a second aspect of the present invention, there is provided a switch for exchanging ATM cells transmitted to an ATM switching apparatus, and for reassembling packets from ATM cells transmitted to the ATM switching apparatus. Cell receiving means for receiving ATM cells in a traffic management device for use in said ATM switching equipment also having reassembly means of said ATM switching equipment; said cell receiving means being connected to said cell receiving means and being provided by said reassembly means of the ATM switching equipment 1 requiring reassembly
Or cell identification means operable to identify received cells belonging to a plurality of predetermined packet types as respective reassembled cells; and adapted to connect to said switch body when a device is in use. A second port means separate from said first port means, said first port means being adapted to connect to said reassembly means when the device is in use. Cell output means operable to transmit a received cell other than the identified reassembled cell to the first port means and to transmit the reassembled cell to the second port means. Is provided.

According to a third aspect of the present invention, a switch for exchanging ATM cells, reassembly means for reassembling packets from ATM cells, and receiving ATM cells transmitted to an ATM network exchange. Method for use in said ATM network switching apparatus, including traffic management means for receiving, the received ATM cells belonging to one or more predetermined packet types requiring reassembly by reassembly means. Received by the traffic management means as respective reassembled cells; and the received cells other than such identified reassembled cells are transmitted by the traffic management means to the switch body via the first data delivery path means, and are received by the switch body. The replaced and identified reassembly cell is the first data The reach path means through the second data delivery path means separated, sent to reassembly unit from the traffic management unit, the re-assembly means are reassembled into packets, replacement methods are provided.

In the first to third aspects of the present invention,
Cells requiring reassembly can be sent directly to the reassembly means without having to go through the switch body. Thus, all switch ports of the switch body can be used by traffic management means to exchange non-reassembled cells. Therefore, the switch throughput is increased and the problem of contention in the switching device is reduced.

Packets that require reassembly are, for example, signaling messages (especially AAL5 messages) or inter-host communication messages (especially ATM user network interface (UNI) intermediate intermediate management interfaces (ILM) between management entities.
I) communication). Packets requiring reassembly also include Internet Protocol packets. In this case, the device preferably further comprises internet protocol switch controller means connected with said reassembly means for examining such reassembled internet protocol packets in order to detect packet flow through the switching device. In. The traffic management means can then send the cells required by the internet protocol switch controller means directly to this means without passing through the switch body. Preferably, the traffic management means, in its default routing mode, receives an internet protocol packet from an upstream node of the ATM network via a predetermined default input virtual channel and belongs to said predetermined default input virtual channel. The received ATM cell is identified as such a reassembled cell, and the Internet Protocol switch controller means provides the second means to the reassembly means for detecting the packet flow by inspection of the reassembled packet. It is operable to transmit these cells via the data delivery path means.

[0018] The traffic management means may also include, when such a packet flow is detected by the internet protocol switch control means, via a new input virtual channel different from the predetermined default input virtual channel. By
The cells of the subsequent packets that make up the packet flow after detection are received, these cells are not identified as such reassembled cells, and are transmitted directly to the switch body via the first data delivery path means. Exchange is possible to operate in through exchange mode.

In this way, the cells belonging to the detected flow are exchanged by the Internet protocol switch control device means in the exchange to realize so-called cut-through exchange in which cells of the flow are directly routed in hardware. Can be routed through the switch without being reassembled. For example, when the Internet protocol switch control device detects such a packet flow, the traffic management device is allowed to secure a bandwidth for exchanging cells of the detected packet flow via the switch body.

Preferably, the reassembled packet which is not detected as belonging to the packet flow by the internet protocol switch control means is sent to the switch unit to execute store-and-forward routing of the IP packet which does not belong to the flow. It is segmented into cells that are forwarded back to the traffic management means for transmission. After passing through the switch body, the cells of the plurality may then be output to a downstream node of the ATM network via a predetermined default output virtual channel. On the other hand, while the traffic management means is operating in the cut-through switching mode, the cells of the subsequent packets making up the detected packet flow preferably have a new output different from the predetermined default output virtual channel. Output by the traffic management means via the virtual channel.

In one embodiment, the traffic management means examines a virtual path identifier and / or a virtual channel identifier field of a header of each received ATM cell, and based on the result of the inspection, determines whether the cell concerned has such a function. Cell identification means operable to determine whether to be identified as a proper reassembled cell is included. Thus, reassembly cells can be identified quickly and easily.

Preferably, the apparatus further comprises a segmenting means (the segmenting means and the reassembly means are part of the same segmentation and reassembly device).
Wherein said segmenting means is also connected to said traffic management means by said second data delivery path means, for segmenting a locally generated packet within the device into a plurality of ATM cells, Operable to transmit the cells of the plurality to the traffic management means via the delivery path means. In this configuration, the cells resulting from the segmentation can also be transmitted to the traffic management means without passing through the switch body.

In this case, the second data delivery path means includes respective one-way transmission / reception path means, and the reception path means transmits the identified reassembled cells from the traffic management means to the reassembly means. Works like
The transmission path means functions to transmit the cells of the plurality from the segmenting means to the traffic management means.

In a preferred embodiment, the traffic management means is connected to the switch body by the first data delivery path means for exchanging ATM cells via a data transfer path provided by the switch body. A plurality of individual traffic management devices, wherein the second data delivery path means comprises: a reassembly means; and, if provided, the segmentation means. Bus means (for example, Universal)
-Test-and-Operations-PHY-
Interface-for-ATM (UTOPIA)
Level 2 "looklike" bus means). In this configuration, each traffic management device controls the transmission of cells to one or more associated input ports of the switch body, and each traffic management device directs any reassembly to the reassembly means using bus means. Cells can be sent.

In order to allow different traffic management devices to share the bus means, said reassembly means is operable as a master device of said bus means and each traffic management device is operable as a slave device of said bus means. Is preferred. In this case, for example, the reassembling means may include polling for polling the traffic management device to determine whether any of the traffic management devices identified the received ATM cell as such a reassembly cell. If the polling means determines that one of the means and one of the traffic management devices has identified such a reassembled cell, the traffic management device having that cell disassembles the reassembly means via the bus means. Data reading means operable to transmit the data.

According to a fourth aspect of the present invention, there is provided an exchange for use in an ATM network, comprising:
A switch body for exchanging cells; a segmenting means for segmenting a packet generated locally in the switching device into a plurality of ATM cells; and a first data delivery route means connected to the switch body, Further, cells connected to the segmenting means by second data delivery path means separated from the first data delivery path means, and cells exchanged by a switch body are passed through the first data delivery path means. The plurality of cells received from the switch body and the plurality of cells received from the segmenting means via the second data delivery path means, and the exchanged cells received from the switch body and the plurality of cells received from the segmentation means. A traffic management means operable to output an ATM cell stream comprising: It has been.

According to a fifth embodiment of the present invention, an ATM
A switch for exchanging ATM cells delivered to the switching device, and for segmenting packets locally generated by the device into a plurality of ATM cells to be output from the ATM switching device; A traffic management device for use in an ATM switching device that also has a segmenting means, wherein the first is adapted to connect to the switch body when the device is in use.
And a second port means separate from the first port means, adapted to connect to the segmenting means when the device is in use, and further comprising a switch. Receiving the cells exchanged by the body at the first port means and transmitting the plurality of cells to the second
Cell input means operable to receive at the port means; and cell output means for outputting an ATM cell stream including the exchanged cells received from the switch body and also including the plurality of cells. A traffic management device comprising:

According to a sixth aspect of the present invention, a switch unit for exchanging ATM cells, a segmenting means for segmenting a packet generated locally in an ATM exchange into a plurality of ATM cells, and A including traffic management means for outputting the exchanged cells.
In a switching method used in a TM network switching device: cells exchanged by a switch body are received by a traffic management means from a switch body via a first data delivery path means; a plurality of cells generated by a segmentation means Of cells are received by the traffic management means via the second data delivery path means separate from the first data delivery path means; the exchanged cells received from the switch body and received from the segmentation means. The ATM cell stream including the plurality of cells,
An exchange method output by the traffic management means is provided.

In the fourth to sixth aspects of the invention, the advantages corresponding to the advantages achieved by the first to third aspects of the invention are obtained even if the exchange has no reassembly means. Obtainable. The cells resulting from the segmentation can be transferred directly to the traffic management means without passing through the switch body, freeing the switch port of the switch body for non-segmented cells and reducing congestion.

According to a seventh aspect of the present invention, there is provided an exchange for use in an ATM network, comprising:
A switch body for exchanging cells; an internet protocol switch controller means for detecting an internet protocol flow through the exchange; and a first connected to receive ATM cells transmitted to the exchange, and A data delivery path means is connected to the switch body and a second data delivery path means separate from the first data delivery path means is connected to the Internet protocol switch controller means, and in its default routing mode, is predetermined. The received ATM cells belonging to the default input virtual channel are identified as default routing cells, and these cells are transmitted to the Internet protocol switch control means through the second data delivery path means, and are transmitted to the Internet protocol switch. Col switch controller means is operable to enable detection of such a flow from inspection of transmitted cells, and when such flow is detected by the Internet protocol switch controller means, Subsequent received cells making up the flow detected by the traffic management means via a new input virtual channel different from the received default input virtual channel are received and these cells are not identified as such default routing cells, A switching device is provided that includes traffic management means that can be switched to operate in a cut-through switching mode, such as being transmitted directly to a switch body via a first data delivery path means.

According to an eighth embodiment of the invention, an internet protocol switch controller means having a switch body for exchanging ATM cells transmitted to the device and for detecting an internet protocol flow through the exchange device. In a traffic management device for use in an ATM switching device also having: a cell receiving means for receiving ATM cells; a first adapted to connect to said switch body when the device is in use. A cell output having second port means separate from said first port means and adapted to connect to said internet protocol switch controller means when a device is in use. Means; and a default routing mode connected to the cell receiving means. , Identifying incoming ATM cells as belonging to a predetermined default input virtual channel as default routing cells and sending these cells to said second port means for transfer to said internet protocol switch controller. The internet protocol switch controller means is operable to detect such a flow by inspection of the transmitted cell, and at the time such a flow is detected by the internet protocol switch controller means, Subsequent received cells making up a flow detected by the traffic management device via a new input virtual channel different from the predetermined default input virtual channel will be accepted as this default routing cell. Traffic management comprising cell identification means that can be exchanged to operate in a cut-through exchange mode in which cells of the same are not identified and are sent to the first port means for direct transfer to the switch body. A device is provided.

In the seventh and eighth aspects of the present invention, it is preferable that the internet protocol switch control means has reassembly means for assembling the default routing cell after identification received from the traffic management means. It is unnecessary. Reference will now be made, by way of example, to the accompanying drawings.

[0033]

FIG. 2 is a block diagram of an ATM embodying the present invention.
Fig. 2 shows parts of the switching device. In FIG. 2, portions corresponding to the portions described above with reference to FIG. 1 are denoted by the same reference numerals. In exchange apparatus 21 of FIG. 2, each of the traffic management device 24 ₁ to 24 _N, it has been modified as compared to the traffic management device 4 ₁ to 4 _N-1 as described in FIG. Similar to the apparatus of FIG. 1, each traffic management device 24 _i is connected to its corresponding physical layer device 2 _i using a data delivery path 6 _i (i = 1 to N). Each data delivery path 6 _i has 16 channels for data transfer at up to 622 Mbps (clock frequency ≦ 50 MHz).
Univers providing a bit data path in each direction
al Test and Operations PH
Y interface (UTOPIA) level 2. Thus, each physical layer device 2 and each traffic management device 4 have two ports (one for transmission and one for reception), both of which use the same protocol and interface definition.

For simplicity, FIG. 2 shows only one physical layer device 2 _i connected to each traffic management device 24 _i , but UTOPIA
Level 2 path 6 _i is actually an ATM layer of 155 Mb
When operating at ps, n ≦ 8, ATM layer is 622Mb
When operating at ps, n ≦ 4, allowing up to n physical layer devices to be connected to each traffic management device. The UTOPIA level 2 interface includes five addressing lines, thus providing virtual space for up to 31 ports on up to 8 physical layer devices.

A more complete description of the UTOPIA Level 2 interface can be found in ATM Forum's "U
TOPIA ", ATM-PHY interface specification,
Level 2, version 1.0 ″, June 1995. Each traffic management device 24 _i.
Is connected to a port pair of a switch body 8 composed of an input port and an output port by a data delivery path 10 _i . The data delivery path 10 _i may be of any suitable type, parallel or serial, but in this embodiment the interface to the data delivery path 10 _i provided in the traffic management device 24 _i is a UTOPIA level 2 "Look Alike (loo
(UL2LAL) interface. It basically has the same properties as the above-mentioned UTOPIA Level 2 standard interface published by the ATM Forum, but the UTOPIA standard interface is intended for physical layer devices to connect to ATM layer devices (eg traffic management devices). And is not intended to provide a connection between two ATM layer devices, such as a traffic management device or a switch body, and is therefore described as being a "look-alike" interface of a standard interface. Have been.

The data delivery path 10 _i also includes a parallel / serial converter, so that the path is parallel at the end connected to the traffic management device 24 _i and in series at the end connected to the switch body. It is also possible to make it. Thus, the number of connection pins on the switch body 8 is increased by the applicant's co-pending UK patent application no.
It can be reduced as described in 17110.3. Alternatively or additionally, here again, Applicant's co-pending application Ser. No. 9617110.
As described in No. 3, multiple traffic management devices can be connected to the same port pair on a time division multiplex basis in order to reduce the number of connection pins required on the switch body 8. . This application and the applicant's other co-pending British Patent Application No. 9617100.
The contents of No. 4 are incorporated herein by reference.

Each traffic management device 24 _i is also connected to host processor 16 via host bus 28. The host bus is, for example, a bidirectional 32-bit wide data path with a sufficient number of address lines for individually addressing (polling) _N different traffic management devices 24 ₁ -24 _N. The switching device 21 shown in FIG. 2 comprises, first of all, another bus 26, hereinafter referred to as the SAR bus, to each of the traffic management devices 24 ₁ ... by the fact that is provided to connect the 24 _N, it is different from the exchange apparatus 1 shown in FIG. Therefore, unlike the case of the switching device of FIG. 1, the SAR device 12 is not connected to one of the port pairs of the switch body 8. The SAR bus 26 preferably has a UL width of ビ ッ ト (8 bits of data in each direction).
2LAL interface. In this case, SAR device 12 is a master device having a control for SAR bus 26, each of the traffic management device 24 ₁ to 24 _N is slave device. Or,
The SAR bus 26 is a pin count of the traffic management device 24 and the SAR device 12.
A high speed serial bus may be used to reduce The second bus is a low voltage differential signal (LVDS: Low Volt).
age Differential Signals)
Can be used to transfer

The SAR device 12 may be, for example, an MB86687A type manufactured by the applicant.
Here, the operation of the apparatus of FIG. 2 will be described. However, before describing a detailed description of the device, a broadband digital integrated services network (B-ISDN) that can use the switching device of FIG. 2 will be schematically described with reference to FIG. The switching device of FIG. 2 is not only intended for use within a B-ISDN, but the B-ISDN may include a large number of signaling messages (and between To provide a good example for illustration purposes, because it includes a connection-oriented communication protocol that generates communication messages).
You can also see that SDN is useful. However, all communication protocols used within ATM networks, even connectionless protocols, and inevitably include the generation and processing of signaling messages, embodiments of the present invention favor all such networks. Applicable.

The B-ISDN network 100 shown in FIG. 3 has a plurality of customer premises (CP: Customer premises) respectively corresponding to different customer premises.
s) It has a node 102. At each CP node, the arbitrarily formatted information supplied by the user is converted into an ATM cell stream, and from the reverse direction, the ATM cell stream received from the network is converted into user information in the required format. You. These conversions are performed by the ATM Adaptation Layer (AAL) in the CP node, which acts as a terminal adapter. CP nodes that only generate and receive low-bandwidth ATM cell streams are usually
Connected to a remote multiplexer node (RMN) 106 where the individual low-bandwidth ATM cell streams are statistically multiplexed or demultiplexed onto concentrator link 108. A number of such concentrator links 108 are connected to an access node (AN) 110 to which higher band CP nodes 102 may also be connected by links 112. Access node 110
The highly multiplexed ATM cell stream that emerges from is transmitted to a local switching node (LEN) 114 to which other RMNs 106 as well as ultra-high bandwidth CP nodes 102 can also be connected. The switching device of FIG. 2 can be used in the LEN 114, for example. L
EN 114 is connected to a tandem switching node (TEN) 116, which is a larger ATM switch than LEN 114. Again, the switching device of FIG. 2 can be used in the TEN.

The B-ISDN network 100 shown in FIG. 3 is a connection type network that requires a connection type communication protocol. A connection-oriented protocol is one in which the information flow between different CP nodes is accompanied by a header field containing routing information.
Even in the form of a TM cell, it requires a call setup procedure. The call setup procedure selects a route or route to be used by all ATM cells with a connection, eg link 108 in FIG.
Call volume that appears on each physical link of the network such as
It is controlled by limiting the number of connections that share the link. The routes are chosen to evenly distribute the total load among all network links and packet switching nodes (eg LEN 114 and TEN 116) in order to avoid congestion.

If a new connection is allowed, a "virtual connection" number (ie, a particular virtual path identifier (VPI) and virtual channel identifier (VCI) value) is assigned to the connection, and the number is Appears in the VPI / VCI field of all ATM cells belonging to that connection. The virtual connection number implicitly identifies both the caller and the callee for each packet during call setup. When each switch along the selected route receives information about the assigned virtual connection number using a signaling message, the switch including the virtual connection number
Each time an M cell arrives, each switch is given a routing instruction to follow.

The connection-oriented communication protocol is executed by the call processing function. This function is generally a distribution of functions to processors provided at each of the regionally distributed CP nodes, but for the sake of explanation, the call processing functions may be considered to be performed by a single central processor. . Each CP node has a permanent virtual channel number assigned to it for communication with the central call processor, which is connected to the transport network through a regular CP node. Thus, to the transport network, the call processor appears to be some other user or application. A user at a particular CP node (the "source" CP node) may use another desired C node.
A permanent virtual connection from the CP node to the call processor can be used to request a connection to the P node (the "destination" CP node). The requested connection may be bidirectional to allow full-duplex operation. The call processor uses the permanent virtual connection from the call processor to the destination CP node to query the destination CP node whether the CP node wants to accept the requested connection. If it wishes to accept, the Call Processor will still be at or above the guaranteed minimum level of quality of service currently being enjoyed by each of the other connections already using the route when the requested new virtual connection is loaded. Attempts to find a single path that can be maintained.

If the destination CP node refuses to accept the connection or cannot find a suitable route, the connection is blocked and the source CP node sends a permanent virtual connection from the call processor to the source CP node. Receive information about the fact using signaling messages sent over. On the other hand, if a connection can be set up, all switching nodes along the selected path will be informed by the processor about the new virtual connection number and will receive the appropriate routing instructions. For this purpose, signaling messages are sent from the call processor to the switching node via a permanent virtual connection. These signaling messages are
It needs to be sent to the host processor in the switching node, for example the host processor 16 in the switching device of FIG. The way in which signaling messages are handled within the apparatus of FIG. 2 itself will be discussed in more detail below.

By the way, in addition to permanent (preconfigured) virtual connections, switched (dial-up connectivity) virtual connections can also be used to carry signaling messages. Once the call has been set up, the source and destination CP nodes exchange information over the assigned path (or, in the case of a duplex connection, multiple paths). Each A passing along the assigned route
The TM cell contains the virtual connection number assigned in its header, and only the header is processed (in real time, preferably using VLSI circuits where possible) by the switching node to determine the required routing. You.
Thus, all cells with a given virtual connection follow the same route through the network and are transmitted in the same order in which these cells were created.

If either the source or destination CP node wishes to terminate the call, a similar process as during call setup is used to perform call recovery. Again, source and destination C
A permanent virtual connection is used to send signaling messages between the P node and the call processor and between the call processor and the switching node.

In the network shown in FIG.
Just as they are transmitted in the form of TM cells, signaling messages between the source and destination CP nodes and between the call processor and the switching nodes are transmitted in the form of ATM cells. The conversion of user information and signaling messages into ATM cells is
This is a function of the adaptation layer (AAL).

Referring to FIG. 4 which illustrates the protocol involved in the operation of one of the CP nodes shown in FIG. 3, the ATM adaptation layer for the CP node supports multiple types of services. I would have to User services include connection-based, connectionless and possibly other types of variable bit rate (VBR) services and constant bit rate (CBR) services. VBR services support non-persistent traffic with a variety of different peak data rates, such as burst data traffic, image files, large database file transfers, packet video and packet voice.
CBR services, on the other hand, support sustained traffic with a constant data rate over time, such as digital video and digital voice at 64 Kbit / s. A control signal (signaling message) is provided as yet another VBR service.

The AAL has a user interface for receiving an information signal generated by a user and a control interface for receiving a control signal. The AAL uses the AAL prior to introducing the information and control signals into the ATM network.
It is for converting to a standard format suitable for TM and for reconstructing information and control signals from ATM cells arriving from the network prior to output to the user and control interface.

The AAL is divided into two sublayers as shown in FIG. The Convergence Sublayer (CS) performs the encapsulation / decapsulation function for user generated and control signals. In fact, FIG.
As shown in, for example, AAL3 / 4 and AA
In certain types of AAL, such as L5, CS
The sublayer is a common part conversion sublayer (CPCS: common part converters).
Ion sub-layer) and service-specific convergence sublayer (SSCS). Specific A
A certain number of SSCs to support AL user services
The S protocol is already defined and is currently under development. AAL5 is commonly used for signaling messages.

As shown in FIG. 6 relating to AAL5, at the source CP node, the original user generated information signal or control signal to be transmitted over the ATM network and ultimately to the destination CP node is transmitted. , (After processing in the SSCS, if provided), the CPCS service data unit (CPCS
-SDU) to the CPCS. In CPCS, the signal (CPCS-SDU) is encapsulated in the CPS5 protocol data unit (CPCS-PDU) as its payload, as shown in FIG. The CPCS-PDU also has a padding field which can be up to 47 octets in length and an 8 octet trailer whose format is shown in more detail in FIG. The CPCS-User-to-User (CPS-UU) indication field is
Used to transfer CPCS user-to-user information transparently. Currently, there are 64 trailers
Only the common part indicator (CPI) is used to indicate bit alignment and is set to 0, but future features include identification and operation and maintenance of management messages for fault monitoring purposes and the like. (OAM) Message identification is included. The length field simply indicates the length of the CPCS-PDU payload. The length of the payload is in the range of 1-65535 octets and must be octet aligned. The receiver uses the length field to detect the loss or acquisition of information. The length field is
It is a binary code for the number of octets. CPCS-PDU
Cyclic Redundancy Check (CR) to detect bit errors in
C) Field is used. The CRC coverage covers the entire CPCS-PDU including the padding field, CPCS-UU, CPI and length field.

As shown in FIG. 6, CPCS-P
Although the DU does not have a header, it is possible that a header has already been added by the Service Specific Convergence Sublayer (SSCS), in which case the header should be part of the CPCS-SDU accordingly. become. At this time, the entire CPCS-PDU is a SAR that processes the CPCS-PDU as a single variable length field.
Moved to sublayer (FIG. 4). As shown in FIG. 6, the SAR function at this time is to divide the CPCS-PDU into 48 octet segments, each constituting one SAR-PDU payload. The last segment may require padding to form a total 48 octet payload. SAR-PD
U further includes a 5-byte header as shown in FIG.

In the AAL5 SAR function, the main focus is on efficiency, so that all 48 octets available in the ATM cell payload are used to transmit user or control information. Therefore, to indicate the beginning, continuation or end of a message, the SA
None of the octets of the R-PDU payload are available. Instead, the payload type (PT) field of the ATM cell header is used to detect the beginning, continuation and end of the message by the SAR function. Normal PT information is still transmitted in the PT field, but the ATM-layer-user-to-user is used to generate the payload type coating shown in FIG.
Encoded with ATM-Layer-User (AUU) parameters.

This completes the segmentation process performed by the AAL5 layer. The reassembly process is basically the reverse of the segmentation process and serves to reassemble a message (CPCS-SDU or SSCS-SDU, if applicable) from multiple SAR-SDUs. The ATM layer in FIG. 4 serves to add or remove a 5-byte header to or from each SAR-PDU to form a 53 octet ATM cell. The physical layer serves to load or receive cells from the transmission link medium.
Unless signaling messages are specifically directed to it, the nodes of the ATM network shown in FIG. 3, ie, remote multiplexers, access, local exchanges and tandem exchange nodes, operate only on ATM cell headers. The 48-byte cell payload here is not processed by the ATM network entity and is not even read.

In addition to the various layers shown in FIG. 4, the protocol layer model for the B-ISDN network of FIG. 3 also provides a management plane responsible for managing all user and control layers within the CP node. Including. The management plane is involved, for example, in a call setup procedure. Management plane layers A management entity serves to interface each of the user and control layers, and these layers direct these layers (for local management purposes or for transmission to the management plane of a remote CP node). It is responsible for giving and receiving responses from these layers (generated in the management plane of some remote CP node or generated locally).

Returning now to FIG. 2, the switching device 21 is provided in the switching node of the ATM network shown in FIG. 3, for example its local switching node (LENS) 114 or tandem switching nodes (TENs) 116. The 4N UN1 ports of device 21 link the switching node to other switching nodes or access nodes (A
N) 110 or customer premises (CP) node 102
Connected to different respective ATM transmission lines that link to ATM network entities such as The physical layer devices 2 _{1 to} 2 _N are suitable for transmitting the respective bit streams received from the ATM transmission line connected to the UNI port to the traffic management devices 24 _{1 to} 24 _N which are ATM layer devices. Convert to ATM cell stream. Functions performed by the physical layer device 2 include cell rate decoupling, header error control (HEC) header order generation (sequen).
ce generation) / verification
ation); cell delineation
transmission frame adaptation; transmission frame generation and reproduction; and bit timing. The transmission frame adaptation, generation and regeneration functions are required depending on the information in the physical layer, for example, in ITU-T G.264. 707, G.C. 708, and G. 709 Synchronous Digital Hierarchy (SDH) format, STM-1 format (155.52 Mbit)
/ Sec) or ITU-TG. 751 Plesiochronous Digital Hierarchy (PDH) E3 format (3
This is because it is transmitted in any suitable frame format such as 4.368 Mbit / sec. Other suitable formats include Fiber Distributed Data Interface (FDDI) 4b / 5b as specified by the ATM Forum.

The respective ATM cell streams generated by the physical layer devices 2 ₁ to 2 _N are transferred to the corresponding traffic management devices 24 _{1 to} 24 _N via the respective data delivery paths 6 _{i to} 6 _N. FIG.
1 is a schematic diagram of one of the traffic management devices 24. The traffic management device includes an input unit 32 and an output unit 34. The input unit 32 includes a cell receiving circuit 322, a cell identification (ID) circuit 324, and a cell output circuit 326. The cell output circuit 326 includes a data delivery path 10 that links the input section 32 to an input port associated with the switch body.
SA for linking the first port P1 connected to the transmission part of the
It has a second port P2 connected to the R bus 26.

The cell arriving from the physical layer device 2 to the input unit 32 is received by the cell receiving circuit 322. Under the control of the cell reception circuit 322, the cells arriving at the traffic management device are typically part of the traffic management device or more usually one bus to the traffic management device as shown in FIG. It is temporarily buffered in the receive memory 36 which is another memory device such as a connected static RAM.
The receive memory 36 may include, for example, a plurality of receive queues R each corresponding to N different traffic management devices.
It can be formed as Q _{1 to} RQ _N. As described in further detail below, another receive queue (r
An receive queue) RQ _SAR is also provided in the receive memory 36.

Each reception queue RQ can also be subdivided into a plurality of sub-queues SQ _{0 to} SQ ₃ respectively corresponding to different traffic priority levels. In FIG. 9, priority level 3 (the lowest level) corresponds to available bit rate (ABR) and non-specific bit rate (VBR) traffic, and priority level 2 is non-real-time (non-real-t).
ime) variable bit rate (NRT-VBR) traffic, priority level 1 corresponds to real time (R
T) corresponds to VBR traffic, with priority level 0 (highest level) corresponding to constant bit rate (CBR) traffic.

In the cell identification circuit 324, the cell header of each received cell indicates whether the cell forms part of a signaling or inter-host communication message originating from the host processor of another ATM network entity. Inspected to determine. Such cells can be distinguished from user data cells based on the VPI / VCI field of the cell header.
For example, permanent virtual connections reserved for such signaling and communication of inter-host communication messages may all have a special VCI value of 5, but any suitable VPI value. Thus,
Cells belonging to signaling and inter-host communication messages can be distinguished from other cells that make up normal data messages.

As an example of the signaling message,
A call setup message (as described above) and a point-to-multipoint connection setup message are included. Point-to-multipoint signaling messages also have a VC of 5 since the individual links are set up separately, one at a time.
Use the I value. Other examples of dedicated signaling messages include Meta signaling messages (VPI = Any, VCI = 1) and general broadcast (G).
general Broadcast) signaling (V
PI = arbitrary, VCI = 2) is included. In addition, host-to-host communication messages may include user-defined messages identified by assigning a special VPI / VCI combination to the cells that make up the message. In addition, the host-to-host communication message also includes the "ATM User-Network Interface Specification", version 3.1,
Section 4: Adjacent ATM Us, as described in more detail in the Intermediate Local Management Interface Specification.
NI Management Entities (UMEs: UNI Manager)
Intermediate Local Management Interface (ILMI: Interium Loc) between element entities
al Management Interface) communication can also be included. A cell belonging to such an ILMI communication message may also have one or more specific V
A PI / VCI value (eg VCI = 16, VCI = any suitable value) will be assigned.

When the cell identification circuit 324 determines that the receiving cell is a user-data cell, the destination traffic management device for that cell is identified using the routing table accessible by the input. The cells are then stored in a receive queue RQ (and sub-queue SQ, if provided) corresponding to the destination traffic management device (and cell priority level). In order to enable the host processor to detect congestion in the switching device, the host processor 1 via the host bus 28
6, the filling levels of different reception queues can be read periodically.

The traffic management device operates synchronously in consecutive time slots. In each time slot, the cell output circuit 326 of each traffic management device can transfer one (or possibly multiple) ATM cells to another of the traffic management devices in the device,
The switch body 8 has up to N data transfer paths between one of the input ports and one of the output ports. The cell is output from the first port D1 of the cell output circuit 326. The selection of which receive queue to retrieve cells for transmission from is made by the cell output circuit 326 based on scheduling information provided by the host processor 16 to the traffic management device. In deciding on scheduling, the host processor takes into account the potential for congestion, but to avoid contention issues within the switch, a
Also select a destination pair. These matters are discussed in our co-pending UK patent application no.
Further details in No. 0.3.

After passing through the switch body, the cells reaching the output section 34 of the destination traffic management device are temporarily buffered again in the transmission memory 38. This transmission memory, like the reception memory 36, can be formed as a plurality of transmission queues TQ _{X to} TQ _{X + 3} . Each transmission queue TQ has a corresponding traffic management device 24.
Respectively corresponding to different UNI ports X to X + 3 controlled by the physical layer device 2 connected to the. Each send queue (as in the case of send queue TQ _{X + 3} ) has a different virtual connection VC _{W to} VC _Z or a different priority (as in case of send queue TQ _X ) using its UNI port. may be subdivided into a plurality of sub-queues SQ ₀ ~SQ ₃ corresponding to the level.

On the other hand, when the cell identification circuit 322 in the input unit 32 of the traffic management device 24 determines that the cell received from the corresponding physical layer device 2 belongs to a signal signaling message or an inter-host communication message, The cells are temporarily stored in a further receive queue RQ _SAR corresponding to the SAR device 12.

The different traffic management devices 24 ₁ to 24 ₁
SAR device 12 is a master device for the SAR bus 26 linking to 24 _N is whether any of them continuously polls the traffic management device receives a cell belonging to the communication message between signaling or host Find out. When receiving information from one of the traffic management devices that such a cell has been received, the device reads the cell from the receive queue RQ _SAR to the cell output circuit 326 of the traffic management device and reads the cell. , SA
Command to transmit to the SAR device through the second port P2 through the R bus 26. At this time, the transferred cell is reassembled by the SAR device 12 together with other cells belonging to the same message, and the payload part of the cell is treated as SAR-SDU, (assuming the message is an AAL5 message. P) of cell header
The payload type (PT) information in the T field describes the ATM-layer-user-to-ATM-layer-user (AUU) parameters needed to detect the beginning, continuation and end SAR-SDU of the message. It is decoded for extraction (see FIGS. 6-8 above). The memory device 14 connected to the SAR device 12 is used to store individual SAR-SDUs during message reassembly. Different SARs that belong to the same message
-SDU provides a segment of CPCS-PDU. This PDU contains the CPCS-PDU trailer added by the AAL function at the source of the message. The length field in the trailer is used by the SAR device 12 to detect loss or acquisition of information.
Similarly, the SAR device uses the CRC field to detect bit errors in the CPCS-PDU.
The reassembled message (CPCS-SDU) is then extracted from the CPCS-PDU payload and made available to the host processor 16.

Incidentally, the SAR device 12 can also be used to perform a service-specific convergence sub-layer (SSCS), if present, in which case the CPCS-SDU will send its SDU to the host processor. Prior to sending the
Converted to the requested final message (SSCS-SDU).

The host processor 16 examines the reassembled message and takes appropriate action accordingly. For example, when a new call is set up, a signaling message is sent by the call processing function of the ATM network to inform the host processor about the VPI / VCI fields allocated to the cells belonging to the new connection and to use the new connection. The UNI port of the device to be identified. The information contained in these signaling messages is recorded by the host processor 16 and receives the cells belonging to this new connection as they enter the switching equipment and passes the cells to the appropriate destination traffic management device. The above information is also used by the host processor to update the switch routing table (or address translation circuit) of the traffic management device to be routed.

If the host processor 16 requests to send rather than receive signaling or host-to-host communication messages, the host processor will place it in memory 14 ready for segmentation by the SAR device 12. Store the message. The SAR device 12 sends the message to the CPCS-S.
Treat as a DU (if SSCS in SAR device 12
, The original message is SSC.
It is treated as an S-SDU and first converted to a CPCS-SDU). Next, CPCS-S as its payload
A CPCS-PDU with a DU, padding field and CPCS-PDU trailer is formed (FIG. 7). The CPCS-PDU is then segmented into SAR-SDUs, and each SAR-SDU is used to provide the payload of ATM cells. The PT information in the PT field of the cell header is encoded as shown in FIG. 8 to carry the AUU parameters (AUU = for the cells that make up the beginning and continuation of the message).
0, AUU for cells that make up the end of the message
= 1). The VPI / VCI value needed to route the cell to the intended destination is also
Loaded in the VPI / VCI field of each cell.
For example, the host processor 16 and the destination C
Permanent virtual connections may be reserved for communication between host processors in P nodes or other switching nodes. In this case, the special VPI / assigned to that permanent virtual connection
The VCI value (for example, VCI = 5, VPI value = any) is loaded into the VPI / VCI field of each cell.

The SAR device also identifies the destination traffic management device for the cell belonging to the message, which physical layer device to which it controls the UNI port to which the cell should be output from the switching equipment. Traffic management device. At this time, the SAR device 12 transfers the cell via the SAR bus 26 to the destination traffic management device, and the cell is stored in one of the transmission queues in the transmission queue corresponding to the UNI port to which the cell is to be output. 38. The cell is then transferred from the transmission queue to the UNI port via the physical layer device 2 under the control of the output unit 34 of the traffic management device.

Unlike the switching device of FIG. 1 in which the SAR device is connected to the port of the switch, the device of FIG.
It will be appreciated that the ATM cells that make up the signaling and host-to-host communication messages may be transmitted directly from the traffic management device to the SAR device. Therefore, all ports of the switch body are available for exchanging cells representing user information, which is the preferential information to exchange. Therefore, the device of FIG. 2 can support more UNI ports than the device of FIG. In addition, cell contention within the switch caused by signaling and other messages, since cells destined for the SAR device are bypassed directly to the SAR device by the traffic management device without passing through the switch body. Is avoided.

Although the previous embodiment used the AAL5 communication protocol, this is not essential to the present invention, and in embodiments of the present invention the appropriate It will be appreciated that any communication protocol can be used. Further, in the above embodiment, the cells belonging to the signaling message and the inter-host communication message are
It is designed to be distinguished from other cells based on the VPI / VCI value assigned to it.
Any other suitable method of differentiating signaling / host communication message cells from user-data cells can also be used.

Another embodiment of the present invention will be described below with reference to FIGS. In this embodiment, as shown in FIG. 10, an Internet Protocol (IP) switch 50 located between upstream node 60 and downstream node 70 of the ATM network.
A switching device is used to achieve Upstream and downstream nodes communicate using Internet protocols.

Here, the exchange device 50 in this embodiment.
11, in addition to the components described above with reference to FIG. 2, the switching device 50 further includes an IP switch controller 52 having its own memory 54 and IP switch processor 56. . Memory 5
4 and the IP switch processor 56 are both connected to the host bus 28, which connects the host processor 16 of the switch to each traffic management device 2.
4 Link to ₁ to 24 _N.

Although SAR device 12 is shown in FIG. 11 as part of IP switch controller 52, this is not essential and SAR device 12 is used by both host processor 16 and IP switch processor 56. Therefore, the IP switch control device 52
It may be outside of. The SAR device 12 is connected to the internal memory
The P switch processor 56 and the host bus 28 are connected by extension.

Although the IP switch control device 52 is shown separately from the host processor 16 in FIG. 11, depending on the size of the switching device,
It is also possible to use a single processor to provide and the IP switch processor 56. In this case, the memories 14 and 54 may be combined into a single memory.

The operation of the exchange apparatus of FIG. 11 will now be described with reference to FIGS. By the way, in FIGS. 12 to 15, each traffic management device 2
4 (see FIG. 9) would physically be, for example, both input 32 ₁ and output 34 ₁ would be part of the same traffic management device 24 ₁ . Are shown separately for mere illustration.

[0077] In Figure 12, it is shown the initial operating conditions of the device, wherein the upstream node 60 has established an input virtual channel IVC _DEF predetermined, the IVC _DEF
Is the default forwarding (forwarding) for IP packets between the node 60 and the IP switch 50.
g) Used as a channel. As shown in FIG. 12, in this case, the default transfer channel IVC _DEF
Is assumed to have a traffic management device 24 ₁ as its source traffic management device.

IP from switching device 50 to downstream node 70
The default output virtual channel OVC _DEF is also initialized for use in forwarding packets. As shown in FIG. 12, in this case, the virtual channel OVC
_{The DEF} defaults are assumed to be controlled by the destination traffic management device 24 _N.

The upstream and downstream nodes 60 and 70
Uses Internet Protocol for communication. IP
The packet is transmitted from the upstream node 60 via the switching device 50.
To the downstream node 70. These packets are examples
For example, the length can be up to 64K bytes, and
Each packet is segmented into multiple individual ATM cells
Must be made. Initially, each cell is
When the data is transferred from the code 60 to the switching device 50,
Default input virtual channel IVC_DEFThe first corresponding to
VPI / VCI combination in its header section,
Transfer from the switching device 50 to the downstream node 70
Is the default output virtual channel OVC _DEFCorresponding to
And a second V different from the first VPI / VCI combination.
Has a PI / VCI combination. First VPI / VCI
From the combination of the two to the second VPI / VCI combination
The exchange is performed, for example, by the source traffic management₁
Input section 32₁In the exchange device.

When an IP packet is received for each cell by the input section 32 ₁ of the source traffic management device 24 ₁ via the default input virtual channel IVC _DEF , each cell constituting the packet has a default cell header. since it has a combination of the first VPI / VCI corresponding to the input virtual channel IVC _DEF, it is distinguished from other cells by the input unit 32 _1.

For reasons described in more detail below, the input unit 32
₁ passes the cell of the IP packet to the SAR device 12 via the SAR bus 26. In the SAR device 12, the cells belonging to the same IP packet are combined using the internal memory 54 of the IP switch controller 52 to reassemble the packet. IP
The switch processor 56 runs intelligent routing software for inspecting the reassembled packets in the memory 54 for the purpose of identifying so-called IP flows. When inspected, network traffic is short-lived
It can be classified as traffic or longer "flow" oriented transmission. These flows can be performed by examining each packet to determine the type, eg, file transfer (FTP), or conversation pair (conv).
identified by any of the above. A conversation pair is a series of packets that contain the same source and destination addresses.
Characterized. Flows are unidirectional in nature, suitable for transmission over switched connections,
Thus, as with normal routing processes,
Avoid the processing overhead and delay associated with inspecting individual packets.

In order to allow the switching device to detect a flow and process the packets determined to constitute the flow separately from the packets not identified as constituting such flow, the IP A switch control device 52 is provided. As shown in FIG. 13, if the packet is not part of the flow, it is simply re-segmented into individual cells, and the cell is selected by one of the traffic management devices.
It is transferred to the input unit of one device (for example, the input unit 32 ₂ of the traffic management device 24 ₂ in FIG. 13). This is because in this case, the cell is transferred to the destination traffic management device, which is the traffic management device 24 _N , via the switch body. From here, the cell is the default output virtual channel OVC _DEF
Is output to the downstream node 70. This is the traditional (store-and-forward)
Corresponds to the routing process.

Incidentally, the selection of the traffic management device in which the cells of the segmented packet are to be sent out by the IP switch controller depends on the general (prev
ailing) can be determined according to traffic conditions. Alternatively, the source traffic management device based on the segmented cell (24 _{1 in} this example)
It is always possible to send it back to.

However, this conventional process is different from the IP packet
The entire packet is received by the IP switch controller 52.
Must be stored, stored, and then sent out
Therefore, it is relatively slow. For example,
Packet packets carried by each reassembled packet
Same based on IP identifier or within given period
Reassembled packets with source and destination addresses
That a flow exists based on the number of
If the IP switch control device 52 determines, the IP switch control device 52
The control device 52 transmits the signaling message A (see FIG. 14).
Generate This message A is sent to the SAR device 12
(This allows the signaling message to be segmented into ATM cells.
And one of the traffic management devices 24.
Via the first node to the upstream node 60. Signalin
Message A is transmitted to the upstream node 60 by the flow
Tell the upstream node that it was detected
And the default input virtual channel IVC _DEFUse
Instead, a new input virtual channel IVC_NEWUsing
Send the packet belonging to the flow to the switching device 50
Request to. The switching device 50 has a new virtual channel IV
C_NEWA VPI / VCI combination is proposed.

If the upstream node agrees with the above request and the proposed VPI / VCI combination, the upstream node will be able to access one of the traffic management devices 24 and the SA.
A signaling message B (see FIG. 4) is sent back to the IP switch controller 52 via the R device 12,
From this point onwards, the upstream node has a designated VPI corresponding to the new input virtual channel (IVC _NEW ).
Each cell belonging to the packet of the detection flow having the / VCI combination in the header is sent.

At the same time, the IP switch controller sends a further signaling message C (see FIG. 14) to the downstream node 70 via one of the SAR device 12 and the traffic management device 24. Similar to signaling message A, signaling message C informs the downstream nodes that one flow has been detected and directs traffic belonging to that flow to the new output virtual channel instead of using the default output virtual channel OVC _DEF. Request permission to send to downstream nodes using channel OVC _NEW . Again, the IP switch control device 52
Is the VPI for the new output virtual channel OVC _NEW
/ VCI combination is proposed. If the downstream node 70 agrees with this request and the proposed VPI / VCI combination, the downstream node 70 sends a signaling message D (FIG. 1).
4) to the IP switch control device 52.

Once the new input and output virtual channels IVC _NEW and OVC _NEW have been agreed upon between the upstream node 60, the downstream node 70 and the IP switch controller 52, the IP switch controller 52 will be implemented in hardware. Program the traffic management device in switch 50 to route the flow directly. For example, as shown in FIG. 15, a new input virtual channel IVC _{NE W} is added to traffic management device 24 _N (new “source” traffic management device).
A cell to the input 32 _N of the traffic management device 2 and a new output virtual channel OVC _NEW
4 ₂ downstream node 70 from the output unit 34 ₂ of the (new "Destination" traffic management device), when transmitting cells, IP switch controller 52 with the appropriate address translation data new source traffic management device 24 _N programmed to, thereby, cells received via the new input virtual channel IVC _nEW is identified and passed through by the source traffic management device 24 _N to the destination traffic management device 24 ₂ through the switch body From which the cell is output virtual channel OV
It is output to the downstream node 70 via C _NEW . Thus, cells belonging to the detected flows are no longer transferred from the source traffic management device 24 _N to the SAR device 12 for reassembly and routing, but rather are transferred “automatically” through the switching equipment on a cell-by-cell basis. IP switch controller 52 to transfer through the switching device the cells belonging to the flow, between the source traffic management device 24 _N and destination traffic management device 24 _2, to effectively ensure adequate bandwidth BW _RES.

The ability of a detected flow to bypass the IP switch controller causes the switch to route packets belonging to such a flow at a rate that is limited only by the total throughput of the underlying switch engine. It becomes possible to transfer. Moreover, there is no need to reassemble ATM cells into IP packets in the switching equipment, so throughput is kept optimized throughout the network.

In the above example, the switch to the input virtual channel results in a change in the source traffic management device, but in other cases the source traffic management device is the same for both the default and the new input virtual channel. You will know that you will get it. For example, if there is only one physical path linking the upstream node 60 to a single UNI port on the switch (in this case V
Only the CI needs to be changed, the VPI remains the same), the same applies to the destination traffic management device used to provide the new outgoing virtual channel. It may or may not be the same traffic management device used to provide the default output virtual channel, depending on the placement of the physical path between the switch and the downstream node. .

In the embodiment described above with reference to FIGS. 10 to 15, in order to transmit a packet to be routed on a default store-and-forward basis by the IP switch controller 52 from the source traffic management device to the IP switch controller 52. In addition, the SAR bus 26 is used. Therefore, it is not necessary to connect the IP switch controller to the ports of the switch body, thus leaving all ports of the switch body free to connect to the traffic management device.

The SAR bus 26 can also be used to carry cells belonging to signaling messages A to D that are needed to raise alarms to upstream and downstream nodes for the flow (although in preferred cases). , It is also possible to send signaling messages to the traffic management device via the host bus 28).

[Brief description of the drawings]

FIG. 1 shows parts of a switching device previously considered for use in an ATM network.

FIG. 2 is a diagram showing each part of the ATM switching device according to the first embodiment of the present invention.

3 is a schematic diagram of a broadband integrated services digital communication network (B-ISDN) that can use the apparatus of FIG. 2;

FIG. 4 is a diagram showing a layer model used for explaining a communication protocol used in the network of FIG. 3;

5 shows the ATM adaptation layer (AAL) shown in the model of FIG. 4 in more detail than FIG.

FIG. 6 is a schematic diagram used to illustrate a segmentation and reassembly process according to one type of AAL.

FIG. 7 illustrates one of the data entities utilized in the segmentation and reassembly process of FIG. 6 in more detail than FIG.

8 is a diagram showing the format of an ATM cell utilized in the segmentation and reassembly process of FIG.

FIG. 9 is a diagram schematically illustrating a traffic management device used in the switching device of FIG. 2 and used to explain the operation of the device.

FIG. 10 is a block diagram showing each part of an ATM network including a switching device according to a second embodiment of the present invention.

FIG. 11 is a diagram showing each part of an ATM switching device according to a second embodiment of the present invention.

FIG. 12 is a schematic view (No. 1) used for explaining the operation of the apparatus in FIG.

FIG. 13 is a schematic diagram (part 2) used to explain the operation of the device in FIG. 11;

FIG. 14 is a schematic diagram (part 3) used to explain the operation of the device in FIG. 11;

FIG. 15 is a schematic view (part 4) used to explain the operation of the apparatus in FIG. 11;

[Explanation of symbols]

2 ₁ ~2 _N-1 ... physical device _{4 1 ~4 N-1, 24} 1 ~24 N ... traffic management device 8 ... switch bodies 10 ... data delivery path 12 ... SAR (segmentation and reassembly) device 14 ... memory Reference Signs List 16 host processor 52 IP switch controller 60 upstream node 70 downstream node 100 B-ISDN network 102 customer premises node 106 remote multiplexer node 112 link 114 local switching node 116 tandem switching node 322 cell Receiving circuit 324 ... Cell identification circuit 326 ... Cell input circuit

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 25, 1998

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 7

[Correction method] Change

[Correction contents]

FIG. 7

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Stephen Martin Elby, Manchester Em, UK 259 PEX, Prestwich, Rosa Road, Brentford Court 56 (72) Inventor Graeme Roy Smith, UK, Burleigh bie 9 8 Jayev, Answorth, Hollins Mount, Church Meadow 58

Claims (29)

[Claims] 1. A switching device for use in an ATM network, comprising: a switch body for exchanging ATM cells; reassembly means for reassembling packets from ATM cells; and an ATM transmitted to the switching device. Connected to receive the cell, connected to the switch body by first data delivery path means, and to the reassembly means by second data delivery path means separate from the first data delivery path means. Connected and operable to identify received ATM cells belonging to one or more predetermined packet types requiring reassembly by the reassembly means as respective reassembly cells; Received cells other than such identified reassembled cells are replaced by the first data for replacement by the switch body. Operable to transmit to the switch body via the delivery path means, and the reassembled cells are reassembled into packets by the reassembly means via the second data delivery path means. A traffic management means operable to transmit to the assembling means. 2. The apparatus of claim 1, wherein, as the case may be, the predetermined type of packet or one of the predetermined plurality of types comprises a signaling message. 3. Host means for controlling the operation of the switching device, operatively connected to said reassembly means for receiving packets reassembled by said reassembly means from said reassembly means. Apparatus according to claim 1 or 2, further comprising a host means. 4. A method as defined in claim 1, wherein a packet of the predetermined type or one of the predetermined types is switched by the host means of another ATM network entity to the host of the switching device. Apparatus according to claim 3, comprising an inter-host communication message directed to the means. 5. Optionally, one of said predetermined type or one of said predetermined plurality of types.
Apparatus according to any of the preceding claims, wherein the two types of packets comprise AAL5 messages. 6. The traffic management means includes a cell identification means, which examines a virtual path identifier and / or a virtual channel identifier field of a header of each received ATM cell, and obtains a result of the inspection. Apparatus according to any of the preceding claims, operable to determine whether the cell should be identified as such a reassembled cell. 7. The apparatus further comprises segmenting means connected by said second data delivery path means and also to said traffic management means, said segmenting means for transmitting a locally generated packet within a switching device to a plurality of packets. ATM
7. Apparatus according to any of the preceding claims, operable to segment into cells and to transmit said plurality of cells to traffic management means via said second data delivery path means. 8. The second data delivery path means includes a respective one-way transmission reception path means, the reception path means transmitting the identified reassembled cells from the traffic management means to the reassembly means. 8. The apparatus of claim 7, wherein said transmission path means functions to transmit said plurality of cells from said segmenting means to traffic management means. 9. Apparatus according to claim 7, wherein said segmenting means and said reassembly means form part of the same segmentation and reassembly device. 10. The traffic management means has an AT via a data transfer path formed by a switch body.
A plurality of individual traffic management devices respectively connected to the switch body by the first data delivery path means for exchanging M cells, and wherein the second data delivery path means comprises reassembly means 10. Apparatus according to any one of the preceding claims, comprising bus means for commonly connecting individual traffic management devices to the and to the segmenting means, if provided. 11. The reassembly means is operable as a master device of the bus means, each traffic management device is operable as a slave device of the bus means, and wherein the reassembly means comprises the traffic management device. A received by any of
Polling means for polling each of the traffic management devices to determine whether a TM cell has been identified as such a reassembled cell, and wherein one of the traffic management devices comprises such a reassembled cell. Data reading means operable to cause the traffic management device having the cell to transmit it to the reassembly means via the bus means if the polling means determines that the cell has been identified. The device according to claim 10. 12. The system according to claim 11, wherein said bus means is a Universal.
-Test-and-Operations-PHY-
Interface-for-ATM (UTOPIA)
11. A level 2 (look-alike) bus means.
Or the apparatus according to 11. 13. At least one data port for connecting to an ATM network transmission line transmitting a bit stream when the switching equipment is in use; and one or more data ports for transmitting the bit stream transmitted by the transmission line or each transmission line. 2. The method according to claim 1, further comprising a physical layer means connected between said traffic management means and a data port or each data port for converting said data into a plurality of corresponding ATM cell streams and transmitting said converted ATM cell stream to said traffic management means. The device according to any one of claims 12 to 12. 14. A switching device for use in an ATM network, comprising: a switch unit for exchanging ATM cells;
Segmenting means for segmenting into TM cells,
And a first data delivery path means connected to the switch body, and a second data delivery path means separate from the first data delivery path means and connected to the segmenting means. Exchanged cells are received from the switch body via the first data delivery path means and the plurality of cells are received from the segmentation means via the second data delivery path means and received from the switch body An exchange comprising traffic management means operable to output an ATM cell stream including the plurality of cells received from the switched cells and the segmenting means. 15. An ATM having a switch for exchanging ATM cells transmitted to an ATM switching device and reassembly means for reassembling a packet from the ATM cells transmitted to the ATM switching device. A traffic management device for use in a switching device, comprising: one or more cell receiving means for receiving ATM cells, connected to said cell receiving means and requiring reassembly by said reassembly means of an ATM switching device. Cell identification means operable to identify a received cell as belonging to a predetermined packet type as a respective reassembled cell, and adapted to connect to said switch body when a device is in use. Having first port means which is connected to the reassembly means when the device is in use. Are engaged, said first port means comprises a second port means separated, identified said received cells other than reassembly cell first
A traffic management device comprising cell output means operable to transmit to said port means and to transmit said reassembled cells to said second port means. 16. The method according to claim 16, wherein the cell identification means receives the received AT.
A virtual path identifier in each header of the M cells and / or
16. The method of claim 15, operable to examine a virtual channel identifier field and to determine whether the cell should be identified as such a reassembled cell based on the results of such examination. device. 17. A switch for exchanging ATM cells delivered to an ATM switching device, wherein a packet generated locally by the ATM switching device is transmitted to an ATM switching device.
A traffic management device for use in an ATM switch which also has a segmenting means for segmenting into a plurality of ATM cells to be output from the switch, wherein said device is connected to said switch body when the device is in use. Second port means separate from the first port means and having first port means adapted to connect to the segmenting means when the device is in use Cell input means operable to receive cells exchanged by a switch body at the first port means and receive the plurality of cells at the second port means; and A cell output means for outputting an ATM cell stream including the exchanged cells received from the switch body and also including the plurality of cells. Become a traffic management device. 18. The method of claim 18, wherein the predetermined type or one of the plurality of predetermined types is selected.
One type of packet is an internet protocol packet, and further an internet protocol switch control means connected to said reassembly means for examining such reassembled internet protocol packets to detect packet flow through the switching equipment. The device according to any one of claims 1 to 17, further comprising: 19. The traffic management means receives an Internet Protocol packet from an upstream node of an ATM network via a predetermined default input virtual channel in the default routing mode, and receives the predetermined default input virtual channel. , And identifies the second ATM cell to the reassembly means so that the internet protocol switch controller means can detect the packet flow by inspecting the reassembled packet. Operable to transmit these cells via the data delivery path means of the internet protocol switch controller means when such packet flow is detected by said internet protocol switch controller means.
The cells of subsequent packets making up the packet flow detected by the traffic management means via a new input virtual channel different from said predetermined default input virtual channel are received and these cells are not identified as such reassembled cells 19. The apparatus of claim 18, wherein the apparatus is interchangeable to operate in a cut-through exchange mode such that it is transmitted directly to the switch body via the first data delivery path means. 20. A reassembled packet which is not detected by said internet protocol switch control means as belonging to a packet flow is segmented into a plurality of cells which are sent to said traffic management means for transmission to said switch body. 20. Apparatus according to claim 18 or 19, which is forwarded back. 21. The apparatus of claim 20, wherein after passing through the switch, the cells are output to a downstream node of an ATM network via a predetermined default output virtual channel. 22. During operation of the traffic management means in the cut-through switching mode, a cell of the subsequent packet constituting a detected packet flow has a new output virtual channel different from the predetermined default output virtual channel. 22. Apparatus according to claim 21 output by the traffic management means via a channel. 23. When the internet protocol switch control device detects such a packet flow, the traffic management unit secures a bandwidth for exchanging cells of the detected packet flow via the switch body. Apparatus according to any one of claims 19 to 22. 24. A switching device for use in an ATM network, comprising: a switch body for exchanging ATM cells; an internet protocol switch control device means for detecting an internet protocol flow through the switching device; and a switching device. An internet protocol switch connected to receive the delivered ATM cells and connected to the switch body by first data delivery path means and by second data delivery path means separated from the first data delivery path means; Identify the received ATM cells which are connected to the controller means and which constitute packets which have not been detected as belonging to such a flow in their default routing mode, as default routing cells, and identify these cells as said second data delivery cells. Path hand Traffic management means operable to transmit to said internet protocol switch controller means via said ATM, said traffic management means also comprising a received ATM such as to constitute a packet belonging to such a flow. A switching device operable also in a cut-through switching mode in which cells are transmitted directly to the switch body via said first data delivery path means. 25. A traffic management means operable to receive cells making up a packet via a default input virtual channel in said default routing mode, and controlling said protocol to comprise such a flow with an internet protocol switch control. The device means can switch from the default routing mode to the cut-through switching mode at the time of detection, in which the traffic management means can be switched via another input virtual channel different from the default input virtual channel. 25. The apparatus of claim 24, operative to receive cells that make up a subsequent packet of the detected flow. 26. An ATM switching apparatus having a switch body for exchanging ATM cells delivered to an ATM switching apparatus, and also having an Internet protocol switch control means for detecting an Internet protocol flow through the switching apparatus. A traffic management device for use within, comprising: cell receiving means for receiving ATM cells; first port means adapted to connect to said switch body when the device is in use. A cell output means having second port means separate from said first port means, adapted to connect to said internet protocol switch controller means when a device is in use; and said cell Cell identification means connected to the receiving means, the default routine In the switching mode, received ATM cells which constitute packets not detected as belonging to such a flow are identified as default routing cells, and these are sent to said second port means for transfer to said internet protocol switch controller means. And transmitting a received ATM cell comprising a packet detected as belonging to such a flow to the first port means for direct transfer to the switch body. A traffic management device comprising cell identification means operable in cut-through exchange mode. 27. A switch for exchanging ATM cells, reassembly means for reassembling packets from ATM cells, and traffic management means for receiving ATM cells transmitted to an ATM network switching device. A switching method for use in said ATM network switching device, said receiving A comprising one or more predetermined packet types requiring reassembly by reassembly means.
TM cells are identified by the traffic management means as respective reassembled cells, and the received cells other than the identified reassembled cells are transmitted to the switch body by the traffic management means via the first data delivery path means. The reassembled cell exchanged and identified by the body is transmitted from the traffic management means to the reassembly means via the second data delivery path means separate from the first data delivery path means, and is transmitted by the reassembly means. An exchange method that is reassembled into packets. 28. A switch for exchanging ATM cells, segmenting means for segmenting a packet generated locally in an ATM network exchange into a plurality of ATM cells, and outputting the exchanged cells. A switching method used in the ATM network switching device including traffic management means for receiving, by a traffic management means, a cell exchanged by a switch body from a switch body via a first data delivery path means; A plurality of cells generated by the segmenting means are received by the traffic management means via the second data delivery path means separate from the first data delivery path means, and after the exchange received from the switch body. And said plurality of cells received from the segmenting means. An exchange method in which an ATM cell stream is output by traffic management means. 29. A switch for exchanging ATM cells, an internet protocol switch control means for detecting an internet protocol flow through an internet protocol network exchange, and an ATM cell transmitted to the internet protocol network exchange. A switching method for use in said Internet Protocol network switching device, comprising traffic management means for receiving, wherein a received ATM cell comprising a packet detected as belonging to such a flow is transmitted to a first data delivery path. The received ATM cells, which constitute packets which are transferred from the traffic management means to the switch through the means and are not detected as belonging to the flow, are transmitted from the traffic management means to the previous ATM cells. Replacing the first data delivery path means to be transferred to the Internet Protocol switching controller means via the second data delivery path means isolated.